1. Field of the Invention
The present invention relates to a slurry composition for chemical mechanical polishing (CMP), and more particularly, the present invention relates to a slurry composition for chemical mechanical polishing, which exhibits high polishing rates for barrier metal films and silicon oxide films, is capable of controlling the polishing rate for silicon nitride films, and thereby has a high polishing selection ratio.
2. Description of Related Art
In the chemical mechanical polishing process, which is one of the production processes for semiconductor devices, a polishing process is carried out by mounting on a platen a wafer that is to be subjected to a planarization process, bringing the surface of this wafer into contact with a pad of a polishing machine, and then rotating a rotating plate and the pad of the polishing machine while a slurry is supplied. That is, a slurry flows between the wafer surface and the pad, and polishing of the wafer surface is achieved as a result of the mechanical friction caused by the polishing particles in the slurry and the protrusions at the surface of the pad, while chemical removal is achieved as a result of a chemical reaction between the chemical components in the slurry and the wafer surface.
Generally, the slurry used in a secondary CMP process for copper includes a colloidal silica polishing material, and has a feature of being capable of removing barrier metal films and oxide films in a basic zone. However, in a basic zone, the removal rate of tantalum used as a barrier metal is not so high that a long time is required. Furthermore, since large amounts of polishing materials are used in order to increase the polishing rate for oxide film, there are disadvantages such as particle contamination and high occurrence of scratches.
On the other hand, in an acidic zone, the particle contamination after polishing tends to occur at a lower level than in a basic zone; however, there is a disadvantage that an isoelectric point of the colloidal silica used as the polishing material is reached, and the dispersion stability of the slurry deteriorates.
Furthermore, recently, the degree of semiconductor integration is approaching the physical limit, and a three-dimensional integrated circuit (3D IC) process is under the spotlight. During the 3D IC process, a through-silicon via (TSV) process is used in the wiring production process. However, since the thicknesses of the barrier film, insulating film and polishing preventing film for forming through silicon vias tend to increase, there is a need to polish a barrier film effectively in a short time.